1. Field of the Invention
The present invention relates to a device for driving a rotary valve.
2. Description of the Prior Art
In a prior art rotary valve, as disclosed in, for example, Japanese Unexamined Patent Publication (Kokai) No. 57-176320, rotation control is carried out by a linearly movable drive shaft. An arm is normally fixed onto the valve shaft of the rotary valve, and the tip of the arm and the drive shaft are interconnected by means of a link member. One end of the link member is pivotally connected to the tip of the arm via a pivot pin. The other end of the link member is pivotally connected to the drive shaft via another pivot pin.
Use of such pivot pins, however, is disadvantageous in that the connecting portion between the link member and the tip of the arm and the connecting portion between the link member and the drive shaft loosen when the rotary valve is used for a long time. In addition, when a large number of rotary valves are to be controlled, the number of the pivotally connecting portions increases and, thus, the construction of the link mechanism becomes complicated.